In this project we are studying the genetic control of mating and related cellular processes in the yeast Saccharomyces cerevisiae. We are approaching this study by analyzing mutants that have lost one or more of the functions that are under the control of mating type. Mutants are selected for one of the following defects: inability to mate, inability of produce sex factor, or inability to respond to sex factor. They are characterized with respect to these characteristics and also their ability to sporulate and to repair radiation damage. Genetic tetrad analysis is used to identify the genes associated with the affected functions.